When observing the knee from the side, what does a line that passes anterior to the middle of the knee indicate?

A line that passes anterior to the middle of the knee indicates a hyperextended knee position. In a hyperextended knee, the joint is positioned beyond its normal range of extension, which results in the knee extending forward relative to the supporting structure of the body. This alignment creates a visual cue where the line drawn from the side of the knee appears to be in front of the midpoint of the knee joint, demonstrating that the knee is not in a neutral or flexed position.

In contrast, a neutral knee would show the line aligned with the mid-range of the knee joint, reflecting a standard standing position without excessive extension or flexion. A flexed knee would demonstrate a line that is posterior to the midpoint as the knee bends and moves inward. Lastly, a swollen knee may be present in a variety of knee positions, but it does not specifically correlate to the placement of the line in terms of extension or flexion. Therefore, the anterior placement of the line is indicative of hyperextension.